An expedition finds several new creatures, including a kind of goat

It is hard to imagine that much of scientific interest would be left in the once pristine jungles of Vietnam, site of almost uninterrupted warfare from the 1940s through the mid-'70s. The conflict with the U.S., with its carpet- bombing and wholesale spraying of Agent Orange, was especially devastating. Thus it was something of a surprise that the first scientific foray deep into the Vu Quang Nature Reserve, near Laos, found what amounts to a "lost world" of animal and plant species.

The most exciting discovery: a large, horned mammal that may be a kind of goat. Scientists brought out bones...